Login form and captcha

#1

Anyone using something for this - that works!

#2

Assuming that what you are looking for is something that prevents spam, rather than particularly wanting captcha (ugh!), then I strongly recommend WP Bruiser: https://wordpress.org/plugins/goodbye-captcha/

#3

There is one in s2M (unless it is only for pro), under General Options > CAPTCHA Anti-Spam security.

I use it on my login page: http://scrapbookcampus.com/login